# Study on the Regulation of Diethylene Glycol on the Hydration Process of High-Activity Calcium Oxide

## TL;DR

This study improves calcium hydroxide's performance by using a two-step process involving potassium nitrate pretreatment and diethylene glycol hydration.

## Contribution

A novel two-stage synthesis method enhances calcium hydroxide's reactivity and surface properties for industrial applications.

## Key findings

- Potassium nitrate pretreatment increases calcium oxide reactivity to 435.7 mL.
- Hydration with DEG produces Ca(OH)2 with 98.5% utilization efficiency and 43.24 m2/g surface area.
- The method creates thin platelet structures and prevents particle agglomeration.

## Abstract

Traditional calcium hydroxide (Ca(OH)2) typically exhibits low specific surface area and reactivity, significantly limiting its efficacy in industrial gas–solid reactions such as flue gas desulfurization and thermochemical energy storage. To address these limitations, this study proposes a two-stage synthesis strategy designed to enhance the surface properties and chemical activity of Ca(OH)2. The process involves the preparation of high-activity calcium oxide (CaO), followed by controlled hydration using diethylene glycol (DEG). Drawing on established mechanisms from cement chemistry, wherein potassium ions (K+) catalyze the decomposition of calcium carbonate (CaCO3), limestone particles (10–20 mm) were pre-soaked in a 0.1 mol/L potassium nitrate (KNO3) solution for 48 h prior to calcination. Characterization via X-ray diffraction (XRD), scanning electron microscopy (SEM), and Blaine Air Permeability Method analysis revealed that this pretreatment accelerated decomposition kinetics by inducing surface defects, yielding CaO with a maximum reactivity of 435.7 mL. Subsequent hydration at 80 °C with 70 wt% DEG effectively suppressed particle agglomeration and promoted the formation of thin platelet structures. The resulting Ca(OH)2 achieved a utilization efficiency of 98.5% and a specific surface area of 43.24 m2/g, demonstrating a robust technical route for fabricating high-performance calcium-based sorbents for environmental and energy applications.